We are a little bit unclear about your exact question. We believe that you want to know how to display custom fields in Thank you page. By default, the custom fields will be displayed on the Thank You page.
If you want to show the custom fields in your custom Thank you page then it will automatically display if the default WooCommerce hooks are available in the Thank you page.
Further, the fields created using our plugin are saved in the wp_postmeta table. You can retrieve the value of the custom field from the database by using the below function.
For order metadata, you can use the below function:
$order_meta = get_post_meta( $order_id, $field_name, true );
We hope this will help 🙂
Thank you!